Parking precise alignment control and cotransporter system for rice harvester and transporter

Abstract

In autonomous rice harvesting, the use of transporters to assist rice transportation is an effective way to improve efficiency. However, nonlinear systems, such as double Hydraulic Static Transmission (HST)-driven tracked rice harvesters and transporters, make it challenging to control the precise parallel parking alignment during transportation, often leading to rice loss and potential safety hazards. To address this issue, this study established a geometric cotransporter model and used a preset path to decouple a two-dimensional control problem into two sets of one-dimensional controls. Dynamic and kinematic models of the longitudinal drive and steering systems were analyzed. Based on the identified longitudinal drive system transfer function, a predictive model was constructed to predict and compensate for the parking slip caused by system inertia. It was combined with the integrator wind-up protection to improve the pure tracking method and eliminate or reduce system errors in path tracking. A parallel parking alignment control system was designed using these two methods, and comparative experiments were conducted on the road surface. The results demonstrate that the compensated predictor (CP) longitudinal control improves the alignment accuracy compared with the proportional differential (PD) controller, whereas the Improved Pure-Pursuit Control (IPPC) path-tracking slightly enhances the tracking accuracy compared with proportional integral (PI). Moreover, a field-autonomous rice-harvesting cotransporter experiment showed that the longitudinal alignment accuracy of the designed system was less than 0.2 m. The lateral alignment accuracy was less than 0.1 m.